Re: [Qemu-devel] [PATCH v3 2/2] net: introduce command to query rx-filter information

[Amos Kong]

On Wed, Jun 26, 2013 at 11:54:20AM +0200, Markus Armbruster wrote:
> Amos Kong <address@hidden> writes:
> 
> > We want to implement mac programming over macvtap through Libvirt,
> > related rx-filter configuration contains main mac, some of rx-mode
> > and mac-table.
> >
> > The previous patch adds QMP event to notify management of rx-filter
> > change. This patch adds a monitor command to query rx-filter
> > information.
> >
> > A flag is used to avoid events flooding, if user don't query
> > rx-filter after receives one event, new events won't be sent
> > to qmp monitor.
> >
> > (qemu) info rx-filter vnet0
> > vnet0:
> >  \ promiscuous: on
> >  \ multicast: normal
> >  \ unicast: normal
> >  \ broadcast-allowed: off
> >  \ multicast-overflow: off
> >  \ unicast-overflow: off
> >  \ main-mac: 52:54:00:12:34:56
> >  \ unicast-table:
> >  \ multicast-table:
> >     01:00:5e:00:00:01
> >     33:33:00:00:00:01
> >     33:33:ff:12:34:56
> >
> > Signed-off-by: Amos Kong <address@hidden>

Thanks for your comments, some comments are out-of-data, I removed
them in this reply.

> > +static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc)
> > +{
> > +    VirtIONet *n = qemu_get_nic_opaque(nc);
> > +    RxFilterInfo *info;
> > +    strList *str_list = NULL;
> > +    strList *entry;
> > +    int i;
> > +
> > +    info = g_malloc0(sizeof(*info));
> > +    info->name = g_strdup(nc->name);
> > +    info->promiscuous = n->promisc;
> > +
> > +    if (n->nouni) {
> > +        info->unicast = RX_STATE_NO;
> > +    } else if (n->alluni) {
> > +        info->unicast = RX_STATE_ALL;
> > +    } else {
> > +        info->unicast = RX_STATE_NORMAL;
> > +    }
> > +
> > +    if (n->nomulti) {
> > +        info->multicast = RX_STATE_NO;
> > +    } else if (n->allmulti) {
> > +        info->multicast = RX_STATE_ALL;
> > +    } else {
> > +        info->multicast = RX_STATE_NORMAL;
> > +    }
> 
> Makes me wonder whether replacing VirtIONet members noFOO and allFOO by
> an enum RxState would make things clearer there.  Outside the scope of
> this patch.

Good suggestion, added to my todolist.
 
> > +
> > +    info->broadcast_allowed = n->nobcast;
> > +    info->multicast_overflow = n->mac_table.multi_overflow;
> > +    info->unicast_overflow = n->mac_table.uni_overflow;
> > +    info->main_mac = g_strdup_printf("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
> > +                                     n->mac[0], n->mac[1], n->mac[2],
> > +                                     n->mac[3], n->mac[4], n->mac[5]);
> > +
> 
> Please initialize str_list here rather than at its declaration, because
> that'll make the loop's workings more locally obvious, and because...
> 
> > +    for (i = 0; i < n->mac_table.first_multi; i++) {
> > +        entry = g_malloc0(sizeof(*entry));
> > +        entry->value = g_strdup_printf("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
> > +                                       n->mac_table.macs[i * ETH_ALEN],
> > +                                       n->mac_table.macs[i * ETH_ALEN + 1],
> > +                                       n->mac_table.macs[i * ETH_ALEN + 2],
> > +                                       n->mac_table.macs[i * ETH_ALEN + 3],
> > +                                       n->mac_table.macs[i * ETH_ALEN + 4],
> > +                                       n->mac_table.macs[i * ETH_ALEN + 
> > 5]);
> > +        entry->next = str_list;
> > +        str_list = entry;
> > +    }
> > +    info->unicast_table = str_list;
> > +
> 
> ... it's how this loop works.
> 
> Actually, the two loops are duplicates.  Consider factoring out a helper
> function.
> > +    return info;
> > +}
> > +
> >  static void virtio_net_reset(VirtIODevice *vdev)
> >  {
> >      VirtIONet *n = VIRTIO_NET(vdev);
> > @@ -442,6 +528,8 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, 
> > uint8_t cmd,
> >          return VIRTIO_NET_ERR;
> >      }
> >  
> > +    rxfilter_notify(n->netclient_name);
> > +
> >      return VIRTIO_NET_OK;
> >  }
> >  
> > @@ -495,6 +583,8 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t 
> > cmd,
> >          s = iov_to_buf(iov, iov_cnt, 0, &n->mac, sizeof(n->mac));
> >          assert(s == sizeof(n->mac));
> >          qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
> > +        rxfilter_notify(n->netclient_name);
> > +
> >          return VIRTIO_NET_OK;
> >      }
> >  
> > @@ -559,6 +649,8 @@ static int virtio_net_handle_mac(VirtIONet *n, uint8_t 
> > cmd,
> >          n->mac_table.multi_overflow = 1;
> >      }
> >  
> > +    rxfilter_notify(n->netclient_name);
> > +
> >      return VIRTIO_NET_OK;
> >  }
> >  
> 
> The error returns don't trigger the event.  We can fail after clearing
> n->mac_table.  Why is that okay?

We should notify in error path if n->mac_table is changed.
 
> > @@ -1312,6 +1404,7 @@ static NetClientInfo net_virtio_info = {
> >      .receive = virtio_net_receive,
> >          .cleanup = virtio_net_cleanup,
> >      .link_status_changed = virtio_net_set_link_status,
> > +    .query_rx_filter = virtio_net_query_rxfilter,
> >  };
> >  
> >  static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
> > diff --git a/include/net/net.h b/include/net/net.h
> > index 43d85a1..0af5ba3 100644
> > --- a/include/net/net.h
> > +++ b/include/net/net.h
> > @@ -49,6 +49,7 @@ typedef ssize_t (NetReceiveIOV)(NetClientState *, const 
> > struct iovec *, int);
> >  typedef void (NetCleanup) (NetClientState *);
> >  typedef void (LinkStatusChanged)(NetClientState *);
> >  typedef void (NetClientDestructor)(NetClientState *);
> > +typedef RxFilterInfo *(QueryRxFilter)(NetClientState *);
> >  
> >  typedef struct NetClientInfo {
> >      NetClientOptionsKind type;
> > @@ -59,6 +60,7 @@ typedef struct NetClientInfo {
> >      NetCanReceive *can_receive;
> >      NetCleanup *cleanup;
> >      LinkStatusChanged *link_status_changed;
> > +    QueryRxFilter *query_rx_filter;
> >      NetPoll *poll;
> >  } NetClientInfo;
> >  

> > diff --git a/net/net.c b/net/net.c
> > index 43a74e4..7b73a10 100644
> > --- a/net/net.c
> > +++ b/net/net.c
> > @@ -961,6 +961,53 @@ void print_net_client(Monitor *mon, NetClientState *nc)
> >                     nc->info_str);
> >  }
> >  
> > +RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name,
> > +                                      Error **errp)
> > +{
> > +    NetClientState *nc;
> > +    RxFilterInfoList *filter_list = NULL, *last_entry = NULL;
> > +
> > +    QTAILQ_FOREACH(nc, &net_clients, next) {
> > +        RxFilterInfoList *entry;
> > +        RxFilterInfo *info;
> > +
> > +        if (nc->info->type != NET_CLIENT_OPTIONS_KIND_NIC) {
> > +            continue;
> > +        }
> > +        if (has_name && strcmp(nc->name, name) != 0) {
> > +            continue;
> > +        }
> > +
> > +        if (nc->info->query_rx_filter) {
> > +            info = nc->info->query_rx_filter(nc);
> > +            entry = g_malloc0(sizeof(*entry));
> > +            entry->value = info;
> > +
> > +            if (!filter_list) {
> > +                filter_list = entry;
> > +            } else {
> > +                last_entry->next = entry;
> > +            }
> > +            last_entry = entry;
> > +        } else if (has_name) {
> > +            error_setg(errp, "net client(%s) doesn't support"
> > +                       " rx-filter querying", name);
> > +            break;
> > +        }
> > +
> > +    }
> > +
> > +    if (filter_list == NULL && !error_is_set(errp)) {
> > +        if (has_name) {
> > +            error_setg(errp, "invalid net client name: %s", name);
> > +        } else {
> > +            error_setg(errp, "no net client supports rx-filter querying");
> 
> Why is this an error?

Return an error note is bettr than a NULL list. Management should not query
the rx-filter info if there is no net client supports it.

{
    "return": [
    ]
}

NULL list might be misread to that it supports rx-filter querying, but the
rx-filter config has no item.


> > +        }
> > +    }
> > +
> > +    return filter_list;
> > +}
> > +
> >  void do_info_network(Monitor *mon, const QDict *qdict)
> >  {
> >      NetClientState *nc, *peer;
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 664b31f..cac3e16 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -3619,3 +3619,76 @@
> >              '*cpuid-input-ecx': 'int',
> >              'cpuid-register': 'X86CPURegister32',
> >              'features': 'int' } }
> > +
> > +##
> > +# @RxState:
> > +#
> > +# Packets receiving state
> > +#
> > +# @normal: filter assigned packets according to the mac-table
> > +#
> > +# @no: don't receive any assigned packet
> > +#
> > +# @all: receive all assigned packets
> > +#
> > +##
> > +{ 'enum': 'RxState', 'data': [ 'normal', 'no', 'all' ] }
> > +
> > +##
> > +# @RxFilterInfo:
> > +#
> > +# Rx-filter information for a net client, it contains main mac, some
> > +# of rx-mode items and mac-table.
> > +#
> > +# @name: net client name
> > +#
> > +# @promiscuous: whether to ether promiscuous mode
> > +#
> > +# @multicast: multicast receive state
> > +#
> > +# @unicast: unicast receive state
> > +#
> > +# @broadcast-allowed: whether to receive broadcast
> > +#
> > +# @multicast-overflow: multicast table is overflow or not
> > +#
> > +# @unicast-overflow: unicast table is overflow or not
> > +#
> > +# @main-mac: the main macaddr string
> > +#
> > +# @unicast-table: a list of unicast macaddr string
> > +#
> > +# @multicast-table: a list of multicast macaddr string
> > +#
> > +# Since 1.6
> > +##
> > +
> > +{ 'type': 'RxFilterInfo',
> > +  'data': {
> > +    'name':               'str',
> > +    'promiscuous':        'bool',
> > +    'multicast':          'RxState',
> > +    'unicast':            'RxState',
> > +    'broadcast-allowed':  'bool',
> > +    'multicast-overflow': 'bool',
> > +    'unicast-overflow':   'bool',
> > +    'main-mac':           'str',
> > +    'unicast-table':      ['str'],
> > +    'multicast-table':    ['str'] }}
> > +
> > +##
> > +# @query-rx-filter:
> > +#
> > +# Return rx-filter information for all nics (or for the given nic).
> > +#
> > +# @name: #optional net client name
> > +#
> > +# Returns: list of @RxFilterInfo for all nics (or for the given nic).
> > +#          Returns an error if the given @name doesn't exist, or given
> > +#          nic doesn't support rx-filter querying, or no net client
> > +#          supports rx-filter querying
> 
> NICs, NIC.
> 
> The case "no net client supports rx-filter querying" should return an
> empty list, not throw an error.


 
> I think the case "@name exists but isn't a NIC" should be a separate
> error.

Reasonable.
 
> > +Example:
> > +
> > +-> { "execute": "query-rx-filter", "arguments": { "name": "vnet0" }}
> > +<- { "return": [
> > +        {
> > +            "promiscuous": true,
> > +            "name": "vnet0",
> > +            "main-mac": "52:54:00:12:34:56",
> > +            "unicast": "normal",
> > +            "unicast-table": [
> > +            ],
> > +            "multicast": "normal",
> > +            "multicast-overflow": false,
> > +            "unicast-overflow": false,
> > +            "multicast-table": [
> > +                "01:00:5e:00:00:01",
> > +                "33:33:00:00:00:01",
> > +                "33:33:ff:12:34:56"
> > +            ],
> > +            "broadcast-allowed": false
> > +        }
> > +      ]
> > +   }
> > +
> > +EQMP
> 
> This interface is abstract in the sense that it applies to all NICs.  At
> this time, it's implemented only virtio-net implements it.  I'm
> habitually wary of abstractions based on just one concrete instance,
> which makes me ask:
> 
> 1. Ignorant question first: could the feature make sense for other NICs,
> too, or is it specific to virtio-net?

We will not. 

It's ugly to check if nic is virtio-net nic in net/net.c, so I
register the query function to NetClientInfo. Traversal the net
client list in net/net.c, and execute query of each virtio-net
instance in virtio-net.c

> 2. If the former, are you reasonably sure this object will do for other
> NICs?

No.

-- 
                        Amos.